The formation of silicone networks through the reaction of SiOH-functional and SiH-functional organopolysiloxanes is long known.
U.S. Pat. No. 3,922,443 A describes a composition comprising OH-terminated diorganopolysiloxanes and organohydrogenpolysiloxanes which is preferably used for paper coating and contains up to 1,000 ppm of a platinum metal halide as catalyst.
U.S. Pat. No. 4,071,644 A describes a solvent-free composition comprising OH-terminated diorganopolysiloxanes and organohydrogenpolysiloxanes for production of release coatings which is preferably crosslinked by a tin-containing catalyst.
U.S. Pat. No. 4,028,298 A describes non-stick coatings from siloxane blends which crosslink via condensation reaction of OH-terminated diorganopolysiloxanes and organohydrogenpolysiloxanes and contain a Pt(II) chloride complex with phosphoramide ligands as catalyst.
U.S. Pat. No. 4,262,107 A describes a siloxane blend which crosslinks via condensation reaction of OH-terminated diorganopolysiloxanes and organohydrogenpolysiloxanes and contains a rhodium-based catalyst.
EP 0103639 A1 describes a solvent-free composition comprising OH-terminated diorganopolysiloxanes and organohydrogenpolysiloxanes for production of release coatings which contains a vinyl-terminated polysiloxane gum of high molecular weight (200,000-400,000 g/mol; 0.5% by weight) to speed the condensation reaction.
EP 0186439 A2 describes a siloxane blend which crosslinks via condensation reaction of OH-terminated diorganopolysiloxanes (100 mPas-100,000 Pas) and organohydrogenpolysiloxanes (1-100 mPas) and contains a platinum metal as catalyst and also bis(2-methoxyisopropyl) maleate as inhibitor.
U.S. Pat. No. 5,036,117 A describes a siloxane blend which crosslinks via condensation reaction of OH-terminated diorganopolysiloxanes and organohydrogenpolysiloxanes and contains, preferably, 100 to 300 ppm of a platinum catalyst, a maleic or fumaric diester as inhibitor and also an organic compound (e.g., a primary or secondary alcohol) as pot-life extender.
US 2007/0027286 A1 describes a siloxane blend which crosslinks via condensation reaction of OH-terminated diorganopolysiloxanes and organohydrogenpolysiloxanes and contains an iridium complex as catalyst.
U.S. Pat. No. 5,705,445 A describes aqueous silicone emulsions for coating textiles, which are formed by emulsion polymerization of polysiloxanes bearing SiOH groups with polysiloxanes bearing SiH groups and which contain as adhesion promoter up to 20% by weight of reactive organoalkoxysilanes bearing for example carboxyl, epoxy or amido groups.
WO 2006/083339 A1 describes a resin-filled addition-crosslinking silicone blend for coating textile surfaces which, in addition to the network-forming sil(ox)anes, incorporates adhesion-promoting additives, preferably as a combination of various compounds. These substances comprise high-reactivity silanes, for example (meth)acryloyloxy-functional alkoxysilanes or epoxy-functional alkoxysilanes.
US 2007/054137 A describes addition-crosslinking silicone compositions which also contain condensation-crosslinking reaction partners, for example polysiloxanes bearing SiOH groups. In addition to platinum-based catalysts, condensation catalysts, preferably in the form of zirconium or titanium compounds, and also high-reactivity silanes such as, for example, vinyl-, epoxy-, acryloyl- or acetoxy-containing alkoxysilanes as adhesion promoters are also included.
US 2005/205829 A1 describes silicone coatings for textile surfaces, which contain polyamide resin particles or up to 60% by weight of siloxane resins and up to 30% by weight of CaCO3 to lower the coefficient of friction and, for example, epoxy- or alkoxy-functional silanes as adhesion promoters.
WO 2006/134400 A1 describes condensation- or addition-crosslinking organopolysiloxane compositions which contain kaolin as filler and may contain, for example, epoxy- or alkoxy-functional silanes as adhesion promoters.
WO 02/061200 A1 describes a process for textile coating with silicones wherein the coating is applied in two steps to obtain good adherence to the textile substrate and also a surface having a very low coefficient of friction.
WO 01/12895 A1 describes silicone coatings of not more than 15 g/m2, which in addition to non-reinforcing fillers optionally contain a reinforcing filler such as silica in an amount of not more than 3% by weight in order that very low coefficients of friction may be obtained on coated fabrics.
EP 0953675 A2 describes silicone compositions for textile coatings, which in addition to a reinforcing filler, for example hydrophobicized silica, additionally contain a further filler in at least twice the amount based on the reinforcing filler of laminar shape in order that very low coefficients of friction may be obtained on coated fabrics.
The known compositions have a number of disadvantages. For example, very expensive compounds such as rhodium or major quantities of platinum are used as catalysts. The use of ecologically concerning or poisonous substances such as tin compounds or phosphoramide ligands is as disadvantageous as the need for substances added to achieve the desired properties for the mixtures, for example vinyl-functional polysiloxanes for more rapid curing, or primary/secondary alcohols as pot-life regulators.
The silane compounds often added as adhesion promoters, having hydrolyzable or other reactive groups, raise the costs of such systems and also have the disadvantage that they may cause an appreciable increase in viscosity when used in mixtures with fillers, for example colloidal silica. The increased viscosity has the effect that the processability of the mixtures is compromised or even rendered unimplementable for certain processing methods that require good flowability.
Compositions which, in addition to compounds from the platinum group, contain further catalysts that speed condensation reactions of hydroxysil(ox)ane or alkoxysil(ox)ane compounds (e.g., zirconium or titanium compounds) have the disadvantage that the pot life is too short for many applications, and/or an increase in viscosity is caused. This has the effect that the processability of such mixtures is compromised or even rendered unimplementable for certain processing methods that require a sufficiently long pot life and/or good flowability.
Processes where the silicone layer is applied to the textile support in two or more steps are also disadvantageous in that these methods of operation are more time- and cost-intensive than those where the entire layer of silicone is applied to the textile surface all at once.
The invention therefore has for its object to eliminate the abovementioned disadvantages and to improve the state of the art, more particularly to provide a composition which is very simple to formulate and process and provides coatings having low coefficients of friction and also good adherence to substrates, more particularly to textile substrates, and to provide a process for making it very simple to use the composition of the invention for the coating of textile surfaces.
The object is achieved by the invention.